# P2- Radiation and Life Revision

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• Created by: ElishaG
• Created on: 24-05-16 13:16
What is light?
A type of electromagnetic radiation (EM Radiation).
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A transfer of energy.
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What is visible light?
Radiation our eyes can detect.
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What are the 7 types of radiation that make up the elctromagnetic spectrum?
Radiowaves, Microwaves, Infrared, Visible Light, Ultra Violet, X-Rays, Gamma Rays.
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What do all types of EM radiation transfer?
Transfer energy.
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What is energy delivered as?
Photons (packet of energy).
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What does the amount of energy a photon carries depend on?
The frequency of the radiation.
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What happens to the frequency as you go along the electromagnetic spectrum?
The frequency increases.
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What is an object that emits radition called?
A source.
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As the temperature increases, what happens to heat radiation?
The frequency increases.
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How fast does EM radiation travel in a vacuum?
The speed of light.
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What is the speed of light?
300,000 km/s or 3x10(8) m/s.
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What are three things that happen to radiation once it has been emitted?
Transmitted, reflected, absorbed.
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What does it mean if radiation is transmitted?
It keeps going.
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What does it mean if radiation is reflected?
It bounces back.
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What does it mean if radiation is absorbed?
It's ebsorbed, e.g. sunbather absorbs UV.
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What are objects that absorb called?
Detectors.
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How can you calculate the amount of energy deposited by a beam of photons?
Total energy = number of protons x energy of each photon.
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What does intensity mean?
The amount of energy that arrives at a sqaure metre of surface per second.
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What is intensity measured in?
Watts per square metre (W/m squared).
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Why does intensity decrease as the distance from the source decreases?
The beam spreads out. The beam gets partially absorbed as it travels.
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What is ionisation?
When a photon that has enough energy removes an electron and changes the atoml.
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What are the 3 types of ionising radiation?
Ultraviolet, X-rays and Gamma rays.
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What can happen to cells if they're exposed to ionising radiation?
Can cause mutations, cells may divide over and over- this is cancer.
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What happens if someone is exposed to very high doses of radiation?
Cells can be killed- called radiation sickness.
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What can UV radiation from the sun cause?
Sun burn and possibly skin cancer.
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How can you protect yourself from UV radiation?
Clothes, sunscreen/sunblock.
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How can you protect yourself from X-rays?
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What are X-rays used for?How do they work?
Take pictures of bones to see if they're broken. X-rays absorbed by flesh but not by bones or metal.
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What does non-ionising radiation do when it is absorbed?
It transfers energy to the substance's atoms or molecules and heats them up.
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How can the heating effect affect humans>
It can damage living cells, e.g. you get burned if you absorb too much infared.
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How is the heating effect useful?
It's how we cook food. Normal ovens use infrared and microwave ovens use microwaves.
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How are microwaves used to cook food?
Microwaves make particles vibrate, which heats them up. Some microwaves strongly absorbed by water molecules so can heat things containing water (food).
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How does the intensity affect the heating?
The higher the intensity, the faster the food cooks.
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What features of a microwave prevent the radiation from escaping?
Metal cases and screens over glass doors which reflect and absorb microwaves,
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What are health concerns over microwaves?
1)When you make phone call, microwaves emitted, some absorbed by body, causes heating of tissues(containing water).2)Concerns heating of brain and jaw could increase risk of conditions like cancer.No evidence.
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Why are people who live close to telephone masts worried?
Health effects. Not much evidence, could take years for problems to emerge.
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What do the gases in the atmosphere do?
Filter out some types of radiation from sun. Absorb and reflect radiation, so it never reaches Earth's surface.
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Which types of radiation can easily get through Earth's atmosphere?
Visible light and radio waves.
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Explain the greenhouse effect.
1)Gases absorbing radiation heats Earth's surface up. Some emitted into space-cools Earth down.2)Most radiation emitted is infrared.3)Lot of infrared absorbed by atmospheric gases,inc. CO2,methane and water vapour.4)These gases re-radiate heat in ...
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Greenhouse effect continued...
all directions, including back towards Earth.5)Atmosphere acts as insulating layer and stops Earth losing all heat at night.6)Known as Greenhouse effect.
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Explain the ozone layer.
1)Ozone absorbs UV radiation. Ozone=O3.2)Occurs naturally in atmosphere(the ozone layer).3)When O3 absorbs UV, splits into O2 +O. Reaction is reversible.4)Ozone amount constant but loss of ozone can cause holes.5)Without ozone, more UV....
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Ozone layer continued...
6)UV is ionising so can be very harmful to complex organisms.7)Ozonel ayer very important, protects from too much UV.
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How is carbon dioxide returned to the atmosphere?
1)Respiration in plants and animals. 2)Respiration in decomposers.3)Burning.
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How is carbon dioxide removed from the atmosphere?
By photosynthesis in green plants and other organisms.
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What has happened to the concentration of Carbon dioxide in the atmosphere over the last 200 years?
It has been increasing.
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Why has the amount of Carbon dioxide increased
1)Lifestyles have changed, e.g. use more electrical gadgets, cars and planes- all require energy that we get from burning fossil fuels.2)Population ia rising, more land needed to build and grow food. Space made by chopping and burning trees.
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What is the link between the concentration of carbon dioxide and the global temperature?
Rise in Carbon dioxide is increasing, so is the global temperature.
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How is a rise in Carbon dioxide causing global warming?
It is increasing the greenhouse effect.
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What is global warming?
A type of climate change.
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What is a climate model?
1)Equations that link the atmosphere, oceans and land conditions.2)Once equations inputted, data needed, e.g. temp of ocean to work out speed of currents and air temp.3)Climate models show that global warming isn't natural.
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What are the consequences of global warming?
1)Water expands when hot-Sea levels rise- low lying places flooded.2)Ice melt-sea levels rise.3)Change in weather patterns-more extreme weather.4)Stronger winds, more rain/storms.5)Changing weather can affect food production.
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Name 3 types of radiation and their uses.
Infrared-TV remote controls and night vision cameras. Microwave-Mobile phones and satellite communication. Radio waves-TV and radio transmissions and radar.
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What are radio waves and microwaves good at?Why?
Transmitting information over long distances because they aren't absorbed as much by the Earth's atmosphere.
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What are the wavelengths for TV and FM radio like compared to most radio waves?
Very short wavelengths.
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What are the wavelengths for mobile phone communications like compared to microwaves and radio waves?
Very long wavelengths but small compared to radio waves.
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Explain how satellite communication works.
1)Signal from transmitter is transmitted into space.2)Then absorbed by receiver dish orbiting thousands of km above Earth.Satellite transmits signal back to Earth in different direction.3)Received by satellite dish on ground-metal reflects waves.
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Which types of radiation are used in optical fibres?Why?How do they work?
Infrared and Light as the signal doesn't weaken much because glass doesn't absorb much radiation. Work by bouncing waves idd the sides of thin inner core of glass or plastic.Refracted until it emerges at other end.
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What is all information converted to before it's transmitted?
Electrical signals.
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How can electrical signals be sent/transmitted?
1)Telephone lines.2)Mixed onto carrier EM waves. Then sent out on analogue or digital signals.
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What values can analogue signals have?
Any value in a particular range.
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What values can digital signals have?
one of a small number of discrete values, e.g. 0 or 1, on or off, true or false.
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How is digital information carried?
By switching the EM carrier wave on or off. Creates pulses of waves e.g. 0=off(no pule) and 1=on(pulse).
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What happens when a signal has been transmitted/sent?
A digital receiver will decode the pulses to get copy of original signal.
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Why do signals have to be amplified?
Both analogue and digital weakedn as they travel, may need to be amplifies. Also pick up interference or noise.
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Where do signals get interference or noise from?
Electrical disturbances or other signals.
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Which signals are better quality?
Digital.
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Why are digital signals better quality?
1)Noise less of problem, easy to remove noise.Difficult to know what original analogue signal looked like.2)Transmit several signals at once using one cable or wave3)Digital easier for computers to process.4)Digital info higher quality-more memory.
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## Other cards in this set

### Card 2

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A transfer of energy.

### Card 3

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What is visible light?

### Card 4

#### Front

What are the 7 types of radiation that make up the elctromagnetic spectrum?

### Card 5

#### Front

What do all types of EM radiation transfer?